SmtpClient.Send(消息);错误

Question

我用这个发送电子邮件，但是当我提交时，它显示 "Line 41: smtp.Send(msg);" 错误。我不知道这有什么问题。感谢您的帮助！

 public partial class Contact : Page
    {
        protected void btnSubmit_Click(object sender, EventArgs e)
        {
            MailMessage msg = new MailMessage();
            msg.From = new MailAddress("xxxxx@gmail.com");
            msg.To.Add("xxxxx@hotmail.com");
            msg.Subject = txtSubject.Text;
            msg.Body = txtFirstName.Text + " " + txtLastName.Text + "'s phone number is: " + txtPhone.Text + ". <br />" + "Email Address is: " + txtEmail.Text + "Message: <br />" + txtMessage.Text;
            msg.IsBodyHtml = true;

            SmtpClient smtp = new SmtpClient();
            smtp.Host = "smtp.gmail.com";
          
            System.Net.NetworkCredential NetworkCred = new System.Net.NetworkCredential();
            NetworkCred.UserName = "xxxxx@gmail.com";
            NetworkCred.Password = "xxxxx";
            smtp.UseDefaultCredentials = true;
            smtp.Credentials = NetworkCred;
            smtp.Port = 587;
            smtp.EnableSsl = true;
            smtp.Send(msg);
            lblMessage.Text = "Email has been successfully sent!";

        }
    }

Stack Trace: 


[SmtpException: The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.5.1 Authentication Required. Learn more at]
   System.Net.Mail.MailCommand.CheckResponse(SmtpStatusCode statusCode, String response) +1844406
   System.Net.Mail.MailCommand.Send(SmtpConnection conn, Byte[] command, MailAddress from, Boolean allowUnicode) +46
   System.Net.Mail.SmtpTransport.SendMail(MailAddress sender, MailAddressCollection recipients, String deliveryNotify, Boolean allowUnicode, SmtpFailedRecipientException& exception) +88
   System.Net.Mail.SmtpClient.Send(MailMessage message) +1856
   XinNing_Web.Contact.btnSubmit_Click(Object sender, EventArgs e) in E:\Projects\ASP.NET\XinNing_Web\XinNing_Web\Contact.aspx.cs:41
   System.Web.UI.WebControls.Button.OnClick(EventArgs e) +9767618
   System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument) +204
   System.Web.UI.WebControls.Button.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument) +12
   System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) +15
   System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) +35
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1738

Answer 1

在您尝试发送邮件的 gmail 帐户中允许安全性较低的应用程序为真。

转到我的帐户 -> 登录和安全 -> 允许安全性较低的应用程序（在页面底部）。

由于这个错误发生了一段时间。

SmtpClient.Send(消息);错误

SmtpClient.Send(msg); error

asp.net

system.net.mail

system.net